The history and advancement of fiber optic technology

Fiber Optics

History of Fibre Optics

Advantages and Disadvantages)

Advancement of Fiber Optic Technology

Fiber Optics

The later half of the twentieth century has witnessed dramatic developments in the field of data communication. The tremendous growth in telephone traffic as well as the ever-increasing demands for radio and television transmissions, forced the search for alternative and more efficient data transmission systems. The idea of using light as a carrier of data created a paradigm shift to the telecommunications domain. Simply, the higher frequency of light waves implied that more data could be packed. Being a digital transmission technology, fiber optics became the much preferred communication technique in today's digital world. Fiber optic networks are fast replacing the traditional copper wires in telecommunication networks throughout the world. Let us have a brief overview of the history, the science, the advancements and the application areas for this new age technology.

History of Fibre Optics

John Tyndal, the famous British physicist, discovered the phenomenon of total internal reflection of light in 1870. This discovery is widely regarded as the key to the science of fiber optics. But Alexander Graham Bell's Photophone was the first practical application of light as a medium for carrying data. Graham Bell's photophone transmitted sound waves using light up to a distance of 200 meters. Then in the early fifties the development of the fiberscope, and the introduction of cladding technique to minimize loss of signal made optical transmission a more promising possibility. However, the discovery of laser technology in 1960 was the first major breakthrough in fiber optics. [David R. Goff]. The high power and precision of the laser diode enabled the possibility of focusing a minute area with intense light energy. Gradually in the 1970's the improvement in glass purification process made it possible to limit optical signal loss to less than 20db/km making fiber optics telecommunication systems a practical possibility. Further improvements in the technology of light emitters, as well as fiber production, gradually lessened the signal attenuation below 2db/km and present day optical fibers reach a theoretical minimum optical loss of.2db/km, making optical fibers the most efficient signal transmission medium. [Jeff Hecht]

Design

Optical fibres are nothing but thin strands of highly purified glass that transmit data in the form of light. These individual glass strands have a diameter of around 120 micrometers and are bundled together as optical cables that can transmit data upto 50 Km without the need for repeaters. Each optic fiber can be divided into three distinct layers namely the innermost layer or the core, the cladding layer that immediately covers the core and the outermost buffer coating made of plastic that is designed to protect the fiber from weather and other external damages. While the core is the glass medium on which light travels the cladding layer is used to reflect the escaping light back into the core and thus minimize the optical signal loss. The lower refractive index of the cladding material facilitates reflection of light back into the core region. Thus by using total internal reflection, optical fibres can carry data in the form of light pulses over large distances with little loss. [Craig C. Freudenrich]

The basic fiber optic relay network consist of a transmitter that generates as well as encodes light pulses, an optical fiber that carries the generated pulses, a laser regenerator which is used to energize the weakened signals and finally an optical receiver that decodes the light pulses into electrical signals. The common transmitter wavelengths used in optic fibres are 850 nm, 1,300 nm, and 1,550 nm, ranging from infrared to non-visible regions of the light spectrum. The transmitter lens helps focus the light into the optical fibres with precision and a photodiode in the receiver component detects light. The regenerator is simply an optical fiber coated with a doping material that is exposed to laser beam. Thus, when the signal reaches the doped region the laser beam amplifies it. [Craig C. Freudenrich]

Advancement of Fiber Optic Technology

Fiber optics has evolved a long way over the last decade when compared with the last 50 years with the transmission capacity being increased by more than 200 times. (already in the tera bit region). During the early years fiber optic technology was practically non-viable given the high optical loss of signal (greater than 20 db/km). Then the first generation of fiber optic cables came into existence that confined signal loss to less than 2db/km. Today with dense wavelength-division multiplexing total fiber capacity has been increased up to one terabit and even more. [David R. Goff] We have optical fibres that achieve the theoretical minimum for signal attenuation. Asides telecommunication network, fiber optic technology is today being used for cable television transmissions and for high-speed Internet connections. Optical networks, for military communications is one of the important applications of fiber optics. Also, currently, optical fibres find immense application in the field of medical imaging. The flexibility of the fibres lends itself naturally for less invasive imaging studies like endoscopy, laproscopy, etc. Optical fibres are again highly useful in mechanical imaging for inspection of inaccessible areas of high tech systems. [Craig C. Freudenrich]. Fiber optics is destined to be the future communication medium for real time interactive voice and video communications. Research is already underway in the development of super thin fibres, which are less than 10,000 times, the size of the optic fibres used in present day telecommunication systems. These ultra thin fibres confine light more effectively and thus reduce the need for repeaters every 50 km's. Also, in the near future these fine optical fibres will greatly impact the production of photonic chips that process light impulses. [Philip Ball]

Conclusion

Fiber optic technology has revolutionized the field of Telecommunication. It is the ideal transmission technology for the digital age that we live in where computers have become interwoven with every aspect of our lives. With the drastic improvement in the bandwidth and high performance efficiency there is no question of doubt that optical fibres definitely hold a big advantage over the conventional copper cables. From simple telephone networks, to the development of complex medical and mechanical imaging systems, and production of future technologies such as photonic chips, fiber optics has contributed immensely and thus is destined to be the mainstay communication technology of this age.